Laninamivir octanoate, a long-acting neuraminidase inhibitor, can be used as an effective prophylaxis for preventing influenza following exposure, according to a recent study published in Clinical Infectious Diseases.

Seizaburo Kashiwagi, MD, of the Japan Physicians Association in Tokyo and colleagues performed a double-blind, multi-center study of people who were exposed to influenza by someone they lived with within 48 hours of the infected patient showing symptoms. The researchers reported that most of the study’s participants were between the ages of 30-49 and were parents of infected patients. They also said that approximately 38% had been vaccinated for the 2014-2015 flu season.

Researchers randomly assigned 801 participants into 3 groups. The LO-40SD group of 267 participants received 40mg of laninamivir octanoate via self-activated inhalation in a single dose. The second group of 269 participants, LO-20TD, received 20mg of the drug once a day for 2 days, also by self-activated inhalation and the final group of 265 participants received a placebo.

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Dr Kashiwagi and colleagues then used nasopharyngeal swabs on all participants on the 1st, 3rd and 11th days to test for influenza. If study participants showed symptoms such as temperature above 37.5 degrees C, or had other flu-associated symptoms, they were to report to the clinic for a swab between days 1 and 10.

At the end of the testing period, 4.5%, or 12 of the LO-40SD group contracted the illness; 4.5%, or 13, of the LO-20TD contracted the flu, and 12% (32) of the placebo group had contracted the illness.

Researchers concluded that the single dose of laninamivir octanoate worked and was tolerated well.

“Close contact with an influenza patient increases the risk of subsequent infection. In such cases, antiviral chemoprophylaxis should be considered for persons at high risk from serious illness or death related to influenza (the elderly, those with chronic respiratory illness or metabolic disorders including diabetes mellitus, chronic heart disease, and immunodeficiency),” the researchers concluded.


1. Kashiwagi S, Wantanabe A, Ikematsu H et al. Long-acting neuraminidase inhibitor laninamivir octanoate as post-exposure prophylaxis for influenza. Clin Infect Dis. 2016;63(3)330-37. doi: 10.1093/cid/ciw255.